Flexible conduit system

ABSTRACT

A system of flexible conduit and fittings useful particularly, though not exclusively, for conveying, supporting and connecting electrical service cables and wires. The system includes a corrugated, synthetic resin conduit which is flexible and mechanically strong, connector sleeves for clampingly engaging sections of the corrugated conduit in end-to-end relation, and hanger sleeves for clampingly engaging the conduit and suspending it from a wall or similar surface. A novel electrical outlet box is provided and includes internally toothed conduit-receiving inlet fittings for securely engaging an end of the conduits in inlets to the box.

This is a division of Application Ser. No. 078,376, filed Sept. 24,1979, entitled FLEXIBLE CONDUIT SYSTEM, which is a division ofapplication Ser. No. 875,229 filed Feb. 6, 1978, entitled FLEXIBLECONDUIT SYSTEM, now U.S. Pat. No. 4,248,459.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to protective channel or conveyance systems forconduits, and more particularly, but not by way of limitation, tocorrugated sheathing systems for loosely receiving electrical conductorsextended between remotely spaced locations.

2. Brief Description of the Prior Art

The National Electrical Code in use in the United States containscertain specific and exacting provisions relative to the types of powercable and electrical conduits which can be used in certain wiringsituations and cable conveyance situations, and includes specificationsand criteria to be observed in encasing conductors, electrical wires andcables within certain nonmetallic jackets enclosing conduits. Suchspecifications apply to both surface extensions of cables or conductorsin which the cable or conductors and surrounding nonmetallic jackets aremounted directly on the surface of walls or ceiling, and also aerialextensions in which a supporting cable is used to hang or suspend acased or jacketed electrical cable or conductor. The jackets requiredfor the accommodation of such electrical cable and conductors are, ofcourse, in addition to being nonmetallic, flexible so that the necessaryturns or bends required to carry the cable over a predetermined coursecan be utilized. Good flexibility is thus required of the jacket orconduit which is to contain the electrical cable. It is furtherrequired, of course, that where the nonmetallic jackets or conduits arearranged in end-to-end relation to extend the total length thereof,fittings used for connections shall be such that the electricalconductors are not exposed between the lengths of the conduits or at thefittings. It is also required that at the terminal point of eachconductor, a fitting or box which completely covers the end of theassembly shall be used.

As a result of certain limitations of structural strength believed tocharacterize such nonmetallic conduits as those made of polyvinylchloride and other thermoplastic materials, the specifications of thecode require that conduit having a nominal diametric size of 1/2 inchthrough one inch be supported at intervals which do not exceed 3 feetbetween points of support. Also, in order to avoid short circuiting andfire hazards, the brackets used to support spans of the enclosingconduits are required to be attached to woodwork or plaster, and are notpermitted to contact any metalwork or other electrically conductivematerial. Other requirements exist for aerial cable assemblies supportedupon a messenger line or cable.

In the case of metallic conduits or raceways used to carry electricalconductors, it is required that contact with similar metals (by themetallic raceway) be avoided in order to eliminate the possibility ofthe occurrence of galvanic action. Also, certain restrictions areprovided upon the manner in which metallic raceways can be placed incontact with, or buried in, the earth. These restrictions are based uponthe possibility of deterioration under conditions of corrosion andrusting.

Due to the propensity of such metal raceways to crimp or becomedistorted when they are bent through angles of 90° or more, the codespecifications require that installations which include such bends avoidcrimping of the raceway in a manner which will reduce the effectiveinternal diameter thereof. To this end, limitations are placed on thesize of the radius of curves defined by the inner edge of the metallicraceway in certain installations.

In certain types of installations which use rigid metallic conduit, thematerial of which the conduit or raceway is constructed, must be flameretardent, resistant to impact or crushing, resistant to distortion fromheat under conditions likely to be encountered in service, and resistantto sunlight. It must also, when used underground, be resistant tomoisture and corrosive agents, and sufficiently strong to withstandabuse, such as by impact or crushing loads. Rigid nonmetallic conduit orraceways are required to be supported along their length at each threefoot interval in the case of one-half inch to one inch diameter conduit,and supported at from five up to about eight foot intervals for six inchdiameter conduit. Bends made in such rigid nonmetallic conduit are alsorequired to be formed in such a way that no crimping or reduction ininternal diameter of the conduit results.

In Australian Patent No. 155,417, an electrical wiring system isdisclosed suitable for installation in building structures, and includesat least one central conduit box and a plurality of tubular conduitsextending from the box for receiving insulated electrical conductors.The tubular conduits in each case include at least one relatively shortpiece of corrugated flexible tubing, and at least one relatively longpiece of rigid tubing connected in a relationship such that there is apiece of the flexible tubing interposed between the conduit box and theadjacent end of a piece of the rigid tubing. The ends of the rigidtubing are threaded suitably to form a threaded interlock with thecorrugations of the flexible sections of tubing.

U.S. Pat. No. 3,936,417 to Bonden is directed to a polyvinyl chloridepipe or conduit which is sufficiently flexible to permit it to be coiledup for transport and handling purposes, but has sufficiently high impactand tensile strength to satisfy the most stringent requirements forcommercial installation. The composition prescribed in this patent alsohas a high distortion temperature.

In some instances, such as in a flexible cable shield developed by IBMand disclosed in the IBM Technical Disclosure Bulletin, Volume IX, No.2, July of 1966, flexible corrugated cable shields or conduits have beenmade in two semicylindrical parts which can be folded into a cylinderabout an interconnecting hinge, or coupled together by pairs of matingflanges located at opposite sides of the two semicylindrical parts.

A modular cellular conduit assembly consisting of a plurality ofcorrugated conduit or pipe sections adapted for use as an undergroundinstallation for carrying telephone lines, electrical lines and similarconductors is described in U.S. Pat. No. 3,693,664. The individualcorrugated pipe or conduit sections used in the assembly are eachflexible to facilitate shipment and installation.

A desideratum which existed for a number of years, and was allegedlysolved in 1955 by the patentees in U.S. Pat. No. 2,728,356, was thefabrication of a large diameter, thin walled flexible plastic tubing. Adifficulty which existed with tubing of that sort as it had beenpreviously provided was then when subjected to bending, it tended toundergo buckling or crimping, thus undesirably reducing the internaldiameter of the tubing. The patentees proposed to overcome the problemby providing a plurality of contiguous corrugations in the tubing inwhich the minimum radius curvature of any portion of the ridges andvalleys of the corrugations of the tubing was at least three times thewall thickness at that portion of the corrugated tubing. The patenteesprovided, moreover, that the crest of the ridges and valleys of thecorrugations must constitute long arcs of at least 150°, and not morethan 270°. The ridges and valleys of the corrugations were each arcsformed about a radius away times the thickness of the tubing wall.Further, the patentees contemplated that in the most preferred form, theridges and valleys of the corrugation have an identical radius. Thisallegedly resulted in uniform distribution over a wide area of thestresses arising from bending of the flexible tube, without aconcentration of stress in any one narrow zone.

U.S. Pat. No. 3,060,069 discloses a plastic corrugated tubing useful forenclosing electrical conductors, and particularly of value in providingheat insulation for high resistance electrical conductors.

A corrugated flexible conduit which can be transversely flexed or bentwithout danger of collapsing or crimping, but which is incapable ofundergoing axial stretch, is disclosed in U.S. Pat. No. 2,891,581. Thistubing, however, is made of a rubber composition.

An objectionable characteristic of many types of corrugated tubingproposed as raceways or sheaths for electrical conductors in the priorart is that after bending through a relatively short radius, a tendencyexists for the tubing to spring back or to undergo a reduction in radiusof curvature at the bend location due to the elastic properties of thematerial, and the nature of the corrugations formed therein. Thisdifficulty is allegedly overcome by the particular material ofconstruction used in a corrugated tubing having unconventionalcorrugations therein, as shown and described in U.S. Pat. No. 3,908,704.In short, the side walls of each corrugation are of unequal leng orstated differently, the principal axis of each corrugation extends at anacute angle to the longitudinal axis of the tubing or conduit in whichthe corrugations are formed. This enables each corrugation to fold inunder an adjoining corrugation without kinking or reduction in theeffective internal diameter of the tubing when bends are made on a verysmall radius. A suitable plastic of which this tubing may be made isflexible polyvinyl chloride. It is pointed out in the patent that wherethe corrugated tubing is used as a cable or harnessed dielectric forconductors, a substantial advantage is obtained as a result of the verygood dielectric properties of the plastic of which the tubing is made.

U.S. Pat. No. 3,132,415 indicates it as a criteria or corrugatedelectrical sheathing or conduits that such conduits be manually coilablein bends of various radii which can be as short as five times theoutside diameter of the conduit if necessary. It is also desirable thatthe conduit be sufficiently resilient that it can be restored to itsoriginal straight form, without residual bend deformations as it isinstalled. The conduit has high impact resistance (of the order of 0.9foot-pounds per inch according to ASTM D-256). The corrugated conduit orconductor made in accordance with this patent is said to be capable ofreadily elongating and contracting with temperature changes, withoutbowing out between points of support, or buckling at supports. However,the conduit can elongate or shorten as bridge members move as a resultof expansion or contraction, without any harm being done to theassembly.

A corrugated electrical conduit for containing electrical conductors isdisclosed in U.S. Pat. No. 3,892,912. In this conduit, the corrugationshave flat troughs and crests which extend parallel to the axis of theconduit, and the side walls of each of the corrugations are of equallength. The crests, however, are of greater length, as measuredlongitudinally along the conduit, than are the troughs.

The standards and specifications established by UnderwritersLaboratories for rigid nonmetallic conduits constructed of polyvinylchloride, polyethylene and similar materials require that the conduit beused at a temperature not higher than 50° C. with wiring rated, in anycase, not higher than 90°. The specifications further provide that suchconduit or fittings shall provide a smooth internal raceway for thepulling in of wires and cables, and that such conduits shall not bethreaded. For a so-called heavy wall PVC conduit, specifications ofUnderwriters Laboratory require that a wall thickness ranging from 0.109to 0.129 inch be characteristic of conduit having a nominal 1/2 inchdiameter, and that a wall thickness ranging from 0.28 to 0.314 becharacteristic of heavy wall PVC conduit having a nominal diameter of 6inches. For a so-called thin-walled PVC conduit, the 1/2 inch conduitmust have a wall thickness ranging from 0.060 to 0.080 inch. Four inchconduit of the thin-walled type must have a wall thickness of from 0.15to 0.17 inch.

The Underwriters Laboratory specifications further require that elbowbends in a conduit effected through connection of elbows to a straightsection of the conduit be such that the bend is free of kinks andcreases. It is further required that for this straight walled,noncorrugated conduit, no bends shall be sharper than 90°. For a 1/2inch conduit, the radius of a bend in the conduit can be no smaller thanfour inches. For a six inch conduit, the radius needs to be no smallerthan thirty inches. For all types of PVC conduit, the tensile strengthmust be not less than 5,500 pounds per square inch. The specificationsand standards of Underwriters Laboratory further provide certaincrushing specifications. For example, a 1/2 inch straight wall conduitmust not undergo a reduction of more than 30% in its internal diameterwhen a six inch specimen of the conduit is subjected to a 1000 poundloading imposed upon the central portion conduit. For thin walled PVCconduit, the same reduction in internal diameter must not be exceededwhen a load of 300 lbs. is centrally imposed upon a six inch specimen.For a six inch diameter conduit, the specified reduction in internaldiameter must not be exceeded under a load of 850 lbs. in the case ofthe heavy-walled conduit. Certain impact strength requirements are alsoimposed upon both the heavy-walled and thin-walled conduit.

Corrugated conduit suitable for underground burial and for thecontainment and conveyance of telephone cables and the like ismanufactured and marketed under the trademark "CORFLO" by Haskon, Inc.of Middletown, Del. The CORFLO underground corrugated duct is claimed tohave high crush resistance, and high flexibility which allows elbows andbends to be easily formed in the duct. The CORFLO corrugated duct ismade of high density polyethylene, and is sold in sizes of from 11/2inches up to 4 inches. The impact resistance of the CORFLO polyethylenecorrugated duct ranges from about 40 foot-pounds for 11/2 inch duct upto about 150 foot-pounds for 4 inch duct as determined by ASTM D-2444-70TUP B.

BRIEF DESCRIPTION OF THE PRESENT INVENTION

The present invention provides a system of flexible, synthetic resinconduit and fittings useful particularly, though not exclusively, forconveying, supporting and connecting electrical service cables and wiresbetween separated locations of supply and service. The system includes aunique, corrugated, synthetic resin conduit which is very flexible andmechanically quite strong, but which is thin-walled and light, and caneasily be manually manipulated and installed. Connector sleeves areprovided for clamping sections of the corrugated conduit in end-to-endrelation to prevent axial slippage, and hanger sleeves are included inthe system for clamping the conduit in a non-slip engagement, andsuspending it from a wall or similar surface. The connector sleeves andhanger sleeves are made of electrically non-conductive material. A novelelectrical outlet box is provided, and includes internally toothed,conduit-receiving inlet fittings integrally formed in the box forsecurely engaging ends of the corrugated conduits with inlets to the boxby interfitting and physical interference between the corrugations ofthe conduit and the internally toothed, conduit-receiving inletfittings.

An important object of the invention is to provide an improved system offlexible, synthetic resin conduit and fittings used in combinationtherewith, which conduit can be manually bent to a relatively sharp bendof low radius without the elastic memory of the material of constructionof the conduit resulting in its positional deviation, after bending, inthe direction of its original configuration.

A further object of the invention is to provide an improved flexibleconduit of synthetic resin which, though capable of being manually bentinto a variety of configurations involving relatively sharp bends, canbe suspended at spaced locations on a wall or other supporting structurein such a way that it will undergo a relatively small deflection fromlinearity when so suspended, and when carrying electrical cables orconduit.

A further object of the invention is to provide a rigid polyvinylchloride corrugated conduit which has a relatively thin wall (rangingfrom about 0.1 inch to about 0.2 inch), but has a high impact strengthand high crush resistance. The conduit of the invention can be bentthrough bends having a radius as small as four inches without crimpingor undergoing any reduction in internal diameter. The tensile strengthof the PVC corrugated conduit used in the system of the invention is inexcess of 5000 pounds per square inch.

Another object of the invention is to provide a system of flexibleconduit and fittings which can be bent into various shapes to permit itsinstallation in a great variety of locations requiring changes ofdirection of the conduit, and which can be very quickly and easilyinstalled as a result of the manner in which the fittings utilized withthe conduit cooperate with the conduit as the system is installed.

Additional objects and advantages will become apparent as the followingdetailed description of certain preferred embodiments of the inventionis read in conjunction with the accompanying drawings which illustratesuch preferred embodiments.

GENERAL DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in elevation of one arrangement of a system of flexibleconduit and fittings of the invention, and illustrating in section, awall to which a portion of the system is mounted, and an electrical boxforming a portion of the system.

FIG. 2 is a detail view illustrating, in section, the manner in which anend portion of a corrugated conduit forming a part of the system isengaged by a conduit-receiving inlet fitting used at an inlet opening inan electrical box.

FIG. 3 is one form of hanger sleeve, constructed in accordance with thepresent invention, and forming a part of the flexible conduit andfittings system of the invention.

FIG. 4 is a perspective view of one different form of connecting clampwhich can be used in one embodiment of the conduit and fitting system ofthe invention and illustrating this connector clamp as it appears whenopened apart preparatory to receiving the opposed end portions of a pairof sections of corrugated conduit disposed in end-to-end relation.

FIG. 5 illustrates the connecting clamp shown in FIG. 4 as it appearswhen it is in its closed position, and as it is used in conjunction withsynthetic resin closure straps forming a part of the connector clamp.

FIG. 6 is a perspective view of yet another form of connecting clampuseful in another embodiment of the system of the invention, andillustrating this connecting clamp as it appears when it is opened toits conduit-receiving position.

FIG. 7 is a perspective view of the connecting clamp shown in FIG. 6,illustrating this clamp as it appears when it is in its closed,conduit-engaging position.

FIG. 8 is a perspective view of a form of connector sleeve which forms apart of the system of flexible conduit and fittings of the presentinvention.

FIG. 9 is a sectional view taken through the longitudinal axis of theconnector sleeve shown in FIG. 8.

FIG. 10 is a modified embodiment of the connector sleeve illustrated inFIG. 8.

FIG. 11 is a sectional view taken along the longitudinal center line ofthe connector sleeve shown in FIG. 10.

FIG. 12 is a perspective view of another embodiment of a connector clampuseful in the present invention and showing the clamp in its openedposition.

FIG. 13 is a perspective view of the connector clamp of FIG. 12 showingthe clamp in its closed position.

FIG. 14 is a sectional view through the connector clamp shown in FIG.13, and showing in section a pair of corrugated conduit sections clampedthereby.

FIG. 15 is a side elevation view of another form of inlet fitting usedin terminating a corrugated conduit at an opening into an electrical boxin the system of the invention.

FIG. 16 is a view partially in elevation and partially in section of theinlet fitting illustrated in FIG. 15, and showing, in section, a portionof an electrical box in which the inlet fitting is mounted, and indashed lines, a retainer bushing used to mount the fitting in the box.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Referring initially to FIG. 1 of the drawings, the flexible conduit andfitting system of the invention includes a plurality of lengths orsections 10 of corrugated conduit. The corrugated conduit sections 10each have a longitudinal cross-sectional configuration as illustrated inFIG. 2 of the drawings, and preferably include a series of corrugationshaving relatively sharp crests 10a which are interconnected byrelatively sharp or V-shaped troughs 10b. The corrugated conduit 10 ispreferably constructed of polyvinyl chloride which is of the typereferred to in the industry as rigid polyvinyl chloride, contains atleast 80 percent vinyl chloride, and is preferably one of the typesreferred to as Type 1 or Type 2 in the specifications set forth inASTM-D-1784-75. The corrugated conduit 10 can be of varying diametricsize, including conduit having a diameter of up to six inches, butpreferably is between 1/2 inch and 1 inch in diameter.

The wall thickness of the conduit, as measured normal to the plane ofone of the wall sections extending from a trough to a crest of one ofthe corrugations, is preferably about 0.1 inch to about 0.13 inch in thecase of the 1/2 inch diameter conduit, up to a wall thickness, assimilarly measured, of from about 0.13 inch to about 0.20 inch in thecase of the 1 inch diameter conduit. This relatively thin wall thicknesscharacteristic of the corrugated conduit, when constructed of a rigidpolyvinyl chloride, permits the lengths of the conduit to be bent freelyand easily by hand from a linear configuration to a selectedconfiguration in which the bend in the conduit may define an angle assmall as 90° or less. In most instances, however, installationrequirements will not require bends greater than 90°. In such cases, theconduit can be bent upon a relatively small radius, if desired. Forexample, conduits within the preferred diametric size range of from 1/2inch to 1 inch can be easily bent upon a 4 inch radius without crimpingor reduction of the internal diameter of the conduit, and withoutfatiguing, stressing or cracking of the tensioned, radially outer wallof the conduit.

In the particular arrangement of the system illustrated in FIG. 1,several forms of fitting components used in the system are illustrated,and a novel synthetic resin electrical box 11 adapted to receive andsecurely engage free ends of the conduit is illustrated. Referringinitially to the electrical box 11, such is here shown as being ajunction box rather than a service box, and is used for receiving aplurality of electrical conductors extended through the flexiblecorrugated conduits. Thus, a pair of conductors 12 and 14 are extendedthrough one of the conduit sections, with the conductor 14 then beingextended into a second conduit section along with conductor 16originating in yet a third conduit section. The three conduit sectionswhich carry the conduits 12, 14 and 16 to the interior of the electricalbox 11 are joined to side walls 18 of the box through conduit-receivinginlet fittings, designated generally by reference numeral 20, which arepressed into conduit openings in the side walls of the box.

Each of the inlet fittings 20 comprises an annular element having anaxially extending annular flange 22 which gradually narrows in thicknessto a relatively sharp outer edge, and which has a peripheral, radiallyinwardly extending groove 24 formed therearound. The groove 24 is sizedto receive a circular edge of a side wall 18 of the box at the locationwhere a large circular inlet opening is formed in the respective sidewall. The inlet fitting 20 is thus interlocked by snap engagement withthe respective side wall 18 of the box 11. Such snap engagement iseasily effected by pressing the fitting from the inside of the boxoutwardly, and using the wedging action afforded by the tapered outerside of the annular flange 22 to force the side wall to a position whereit will snap into the groove 24.

Each inlet fitting 20 further includes a radially inwardly extendingreceptor plate 26 which carries a centrally apertured hub 28 at theradially inner side thereof. The hub 28 has a large opening formedthrough the center thereof, and the opening is defined and surrounded bya plurality of annular serrations or sawtooth type grooves which aredimensioned to closely register with the corrugations in the flexibleconduit sections 10. This engagement is illustrated in FIG. 2 of thedrawings. Sufficient flexibility characterizes each of the inletfittings 20 and the end portion of each of the conduit sections 10 topermit the end of the conduit to be forced through the opening in thehub 28 of the fitting, and into registering snap engagement with theserrations formed around the central opening in this hub. Each conduitsection 10 is thus positively interlocked with the electrical box 11.

It will be understood that a suitable cover (not shown) is provided forclosure of the electrical box 11 after the electrical conductors carriedwithin the corrugated conduits 10 have been projected into theelectrical box, and desired connections to, or changes of direction of,the conduits have been effected within the electrical box 11, as may berequired by the particular installation.

The corrugated flexible conduit sections 10 utilized in the system ofthe invention are, in many conventional installations, required toundergo one or more bends of 90°, and to be supported in a horizontalcourse at vertical elevations on walls, or in a particular verticalcourse up the side of a wall. This type of arrangement is illustrated inFIG. 1, where it will be noted that three of the right angle bends,which can be easily accomplished by manual manipulation of the sections10, are illustrated. FIG. 1 of the drawings also illustrates a novelhanger sleeve 30 which can be used in conjunction with the corrugatedconduit sections 10 for the purpose of supporting a conduit section in afixed position on a wall.

The hanger sleeve 30 is illustrated in detail in FIG. 3. This structuralelement is fabricated from an electrically nonconductive syntheticresin, and preferably is rigid polyvinyl chloride of character similarto that of which the flexible conduit 10 is manufactured. The hangersleeve 30 includes a semicylindrical body portion 52 which is joined atone longitudinal edge to a first suspension flange 34 and at the otherlongitudinal edge to a flat side wall 36 which is secured to, and formedintegrally with, a second suspension flange 38 positioned insubstantially coplanar alignment with the flat side wall.

The body portion 32 carries on the inner side wall thereof a firstseries of axially spaced, radially inwardly projecting triangularlycross-sectioned ribs 40 along one side thereof, and a similar secondseries of ribs 42 on the opposite side thereof. The ribs 40 and 42 aregeometrically configured to register with the corrugations in theflexible conduit sections 10 at such time as the hanger sleeve is closedabout a section of the flexible conduit to bring the ribs 40 and 42 intomating engagement with the corrugations of the conduit section. Theclosed portion of the hanger sleeve 30 is illustrated in FIG. 3. It willfurther be noted in referring to FIG. 3 that the suspension flanges 34and 38 each carry facing, interlocking serrations or ribs 44 and 46,respectively, and that these interlocking ribs cause the suspensionflanges, when in abutting registering contact, to index screw-receivingapertures 50 formed through the suspension flanges in alignment witheach other.

In use, the hanger sleeve 30 is first opened by separating thesuspension flange 34 and 38 sufficiently to permit an intermediateportion of a section 10 of the corrugated flexible conduit to beinserted between these flanges, and into the body portion 32 of thehanger sleeve. The hanger sleeve 30 is then closed about the conduit bypressing the suspension flanges 34 and 38 into registering contact witheach other. The character of the synthetic resin material of which thehanger sleeve 30 is constructed assures that such closure will firmlyclamp the hanger sleeve about the conduit section 10. After suchengagement of the hanger sleeve with the conduit section 10, a suitablescrew 42 can be inserted through the aligned screw receiving apertures50 in the suspension flanges 34 and 38 and into a wall 54 or the like tomount or hang the flexible conduit section on the wall at this locationin the manner illustrated in FIG. 1.

In FIGS. 4 and 5 of the drawings, one form of connector sleeve 59 usedin the system of the present invention is illustrated. The connectorsleeve includes a split cylindrical corrugated section of tubing whichincludes a semicylindrical first part 60 and a semicylindrical secondpart 62. The corrugated semicylindrical parts 60 and 62 are joined by aflexible, medial hinge section 64, and a pair of end hinge sections 66and 68 which are each spaced longitudinally from the medial hingesection. The hinge sections permit the parts 60 and 62 to be foldedabout an axis extending longitudinally along the center line of theseveral aligned hinged sections so that the two parts may be moved froman open position, as shown in FIG. 4, to a closed position as shown inFIG. 5. It will be noted in referring to FIGS. 4 and 5 that each of thesemicylindrical parts 60 and 62 has a plurality of contiguous, axiallyarranged circumferential corrugations 70 formed therealong, and thesecorrugations are dimensioned and shaped to facilitate registry with thecorrugations of corrugated conduit sections 10.

When the two parts 60 and 62 are folded about the hinge portions 64, 66and 68 to a closed position as shown in FIG. 5, spaces are providedbetween the end hinge portions 66 and 68 and the medial hinged portion64. These two spaces facilitate the accommodation of a pair of flexiblestraps or bands 72 and 74. The straps 72 and 74 include respective endportions 72a and 74a which carry inwardly facing teeth 76. The teeth 76engage, through a ratchet action, a tongue carried on the inside ofengaging blocks 78 and 80 which are secured to the ends of therespective straps 72 and 74. This structure facilitates the tightsecurement of the straps 72 and 74 about the closed, semicylindricalparts 60 and 62 of the sleeve 59 to retain it in its closed position.

In the use of the connector sleeve, the opposed facing ends of a pair ofconduit sections 10 are placed within one of the parts 60 and 62 of theconnecting sleeve, and the respective conduit sections then project fromopposite ends of this sleeve. After placement of the corrugated conduitsections 10 in a position in which the corrugations in the two sectionsmate or register with the corresponding corrugations 70 on one of thesemicylindrical parts 60 or 62, the other part is then closed about thefacing corrugated conduit sections to tightly engage the pair of conduitsections over a major portion of their periphery through registration ofthe corrugations. The straps 72 and 74 are then placed around theconnector sleeve as shown in FIG. 5 and are tightened about theconnector sleeve and the enclosed conduit section by pulling the endportions 72a and 74a through the gauging blocks 78 and 80 until a tightsecurement is effected.

It should be pointed out that the connector sleeve 59 shown in FIGS. 4and 5 can also be used as a hanger sleeve for suspending or supporting asection of the corrugated conduit on a wall or ceiling. Where such usageof the sleeve is employed, suitable screws or nails are extended throughthe end portions 72(a) and 74(a) of the straps 72 and 74, and into thewall or ceiling to hang or suspend the sleeve at a selected location,and with it the conduit section which extends through the sleeve. Itwill be apparent, of course, that the sleeve 59 shown in FIGS. 4 and 5can also function dually as a connector sleeve and as a hanger sleeve.This is to say that a pair of the corrugated conduit sections 10 can beplaced with their end portions secured within the sleeve in end-to-endrelation, and both sections can then be supported or suspended on a wallor ceiling in the manner described.

In FIGS. 6 and 7 of the drawings, a modified embodiment of connectorsleeve 81 is illustrated. As in the connector sleeve embodiment shown inFIG. 4, a pair of semicylindrical parts 84 and 86 are utilized, andthese parts are interconnected by a flexible hinge portion 88 whichextends along, and interconnects, the opposed, adjacent longitudinaledges of the semicylindrical parts. The hinge portion 88 is sufficientlyflexible that the semicylindrical parts 84 and 86 can be opened apart tothe position shown in FIG. 6 to facilitate the insertion of a pair ofconduit section ends within one of the semicylindrical parts in themanner previously described.

In the embodiment of the connector sleeve 81 shown in FIG. 6, thesemicylindrical part 86 has formed integrally thereon, and adjacent oneof the longitudinal edges of the part, a pair of strap engaging blocks90 and 92. The engaging blocks 90 and 92 function similarly to theblocks 78 and 80 previously described in referring to the connectorsleeve embodiment of FIGS. 4 and 5, and thus serve to receive and engagethe tooth-carrying end portions of a pair of flexible straps 94 and 96.The flexible straps 94 and 96 are formed integrally with thesemicylindrical part 84 and project therefrom at a location adjacent oneof the longitudinal edges of this part of the connector sleeve. When theconnector sleeve 81 is in its closed position, it appears as shown inFIG. 6. It will be understood, of course, that prior to closing theconnector sleeve, one or a pair of corrugated conduit sections isinserted between the semicylindrical parts 84 and 86 which function toeffect interconnection of two sections, or to support a singlecorrugated section or a pair of sections placed in end-to-end relation.

In FIGS. 8 and 9, another embodiment of connector clamp or sleeve 99used in the system of the present invention is illustrated. Theconnector sleeve 99 includes a central or medial cylindrical bodyportion 100 which has smooth outer and inner walls, and which isconnected at its opposite ends to a pair of split jawed clampingportions designated generally by reference numerals 102 and 104. Each ofthe split jawed clamping portions 102 and 104 is substantially identicalto the other, and each includes a pair of movable jaws 106 and 108 whichare hingedly connected by hinges 110 and 112 to one end of the centralbody portion 100 along a medial or arcuate segment of a circle. Themovable jaws 106 and 108 can move, in a pivotal motion, outwardly withrespect to the axis of the connector sleeve.

Each of the movable jaws 106 and 108 on the opposite ends of theconnector sleeve carries a plurality of internal arcuate corrugations109 which are shaped and dimensioned to register with the corrugationsin one of the corrugated conduit sections 10. Each of the movable jawsis also provided on its outer periphery with a relief or recess 113which lies between a pair of shoulders 114 and 116 formed on the outerside of the respective movable jaw. It will be noted that the shoulder114 is formed by the abrupt termination of an axially sloping, arcuaterib 115 which slopes inwardly toward the body portion 100. That portionof each of the movable jaws 106 and 108 lying between the rib 115 andthe respective hinge 110 and 112 by which the jaw is connected to thecentral body portion 100 is smooth, and constitutes a segment of theouter periphery of a cylinder.

Positioned on opposite sides of the connector sleeve 99 from each other,and between each opposed pair of movable jaws 106 and 108 are a pair ofrigid, axially extending semicylindrical side walls 120 and 122. Each ofthe side walls 120 and 122 has a smooth outer peripheral surface formedon a segment of a cylinder, and each has internal corrugations 123 whichare located to occupy a position of axial alignment with thecorrugations 110 in the movable jaws when the movable jaws are closed ashereinafter explained. The corrugations 123 on the side walls 120 and122 are also dimensioned and configured to register with thecorrugations of the corrugated conduit sections 10.

Slidably mounted on the connector sleeve 99 for axial sliding movementtherealong are a pair of annular collars 126 and 128. Each of theannular collars 126 and 128 is of rectangular cross-section, and eachcollar has a transverse dimension which is slightly smaller than thetransverse dimension which is characteristic of the recess 113 asmeasured axially along the connector sleeve 99.

As shown in FIG. 9, the collars 126 and 128 can be slid axially alongthe connector sleeve 99 so that either or both of the collars pass overthe respective arcuate ribs 115 on the movable jaws 106 and 108 at oneend of the connector sleeve and snap into the recesses 112. In thismanner, the movable jaws 106 and 108 are forced to a position of closuresuch that, with the rigid side portions 120 and 122, they form a closedcylinder, the interior of which is lined by the corrugations 109 and 123carried on the movable jaws and rigid wall portions.

A different embodiment of the connector sleeve used in the system of theinvention is shown in FIGS. 10 and 11 of the drawings. The connectorsleeve 130 here illustrated is similar in many respects to the connectorsleeve embodiment shown in FIGS. 8 and 9, and identical referencenumerals have been utilized for identifying identical parts of thesleeve. It will be noted in referring to FIG. 11 that the centralcylindrical body portion 100 of the connector sleeve 130 shown in FIG.11 is somewhat shorter than the central body portion 100 of the sleeveembodiment shown in FIG. 9. As in the case of the earlier describedconnector sleeve, the central body portion 130 has smooth outer andinner walls, and has slidably mounted around the outer periphery thereofa pair of annular collars 126 and 128.

The collars 126 and 128 can slide freely along the central body portion100 and out over a pair of split jawed clamping portions, designatedgenerally by reference numerals 132 and 134, and located at the oppositeends of the central body portion. Each split jawed clamping portion 132and 134 is substantially identical to the other, and each includes apair of movable jaws 136 and 138. Each of the movable jaws 136 and 138is hingedly connected to the central body portion 100 in the mannerpreviously described, and each jaw carries a series of internal, arcuatecorrugations 140 which are shaped and dimensioned to register with thecorrugations in each of the corrugated conduit sections 10. Each of themovable jaws 136 and 138 is also provided on its outer periphery with arelief or recess 142 which lies between a pair of shoulders 144 and 146.It will be noted that the shoulder 146 is formed by the abrupttermination of an axially sloping, arcuate rib 148 which slopes inwardlytoward the body portion. That portion of each of the movable jaws 136and 138 lying between the rib 148 and the respective point of hingedconnection of the jaw to the central body portion is smooth, andconstitutes a segment of the outer periphery of a cylinder.

Positioned on opposite sides of the connector sleeve 130 from eachother, and between each pair of opposed movable jaws 136 and 138, are apair of rigid, axially extending semicylindrical side walls 150 and 152.Each of the side walls 150 and 152 has a smooth outer peripheral surfaceformed as a segment of a cylinder, and a smooth inner peripheral surfacesimilarly formed.

Projecting inwardly from the internal wall of the central body portion100 at a location which is substantially midway between the points ofhinged connection of the jaws 136 and 138 to the central body portion isan annular, radially inwardly projecting stop flange 154.

In the use of the connector sleeve 130 shown in FIGS. 10 and 11, the endportions of a pair of corrugated conduit sections 10 are inserted intoopposite ends of the connector sleeve 130 until the end face of eachcorrugated conduit section abuts against the radially inwardlyprojecting stop flange 154. With the corrugated conduit sections 10 thusaligned in end-to-end relation, and abutted against the stop flange 154,the annular collars 126 and 128 can then be slid axially along theconnector sleeve 130 until these collars pass up over the axiallysloping, arcuate ribs 148 and into the respective recesses 142 carriedon each of the movable jaws 136 and 138 at opposite ends of theconnector sleeve. The corrugated conduit sections are thus clampedfirmly within the connector sleeve in end-to-end relation as previouslydescribed.

Another form of connector clamp useful in the system of the invention isillustrated in FIGS. 12-14, and is designated generally by referencenumeral 160. The connector clamp 160 includes a split body which is madeup of a first split body portion 162 and a second split body portion164. The split body portion 162 is characterized in having asemicylindrical internal wall 166 which has a radially inwardlyprojecting, arcuate, semicylindrical stop rib 168 formed centrallythereon. On its outer side, the split body portion 162 has asubstantially planar surface 170 forming one side wall and intersectinganother substantially planar surface 172. The surfaces 170 and 172 arejoined by a longitudinally extending, radiused corner 174 which extendssubstantially parallel to the axis of the semicylindrical internal wall166.

At the side of the surface 170 opposite its intersection with theradiused corner 174, a slot or groove 178 is formed in the body portion162, and this slot or groove is slightly undercut as shown at 178b inFIG. 13. A final element of the body portion 162 is an axially extendingblock 180 which projects from one end of the body portion to the other,and on its internal side defines a portion of the semicylindrical innerwall 166 of the body portion. The block 180 includes a facing surface180b which is beveled or cut along a plane which intersects at an angle,the plane in which a corresponding facing surface 186 lies on theopposite side of the body portion 162.

The body portion 164 of the connector clamp 160 is formed similarly tothe body portion 162, and thus includes an internal semicylindrical wall182. The internal semicylindrical wall 182 of the body portion 164 has aradially inwardly extending, arcuate semicylindrical stop rib 184 formedcentrally thereon and in alignment with the arcuate semicylindrical stoprib 168 formed on the body portion 162. On opposite sides of the stoprib 184, and at locations spaced axially along the internalsemicylindrical wall 182 of the body portion 164, a pair of radial slots188 and 190 are formed through the body portion, and each slot isprovided with a reduced transverse dimension adjacent the outer side ofthe body portion (not visible) in order to retain an internally flangedlocking plate 192 which is slidably positioned in each of the radialslots 188 and 190. It will be noted, as hereinafter described, that thelocking plates 192 can slide radially in the slots 188 and 190, and eachcarries a radially inner edge which is dimensioned to facilitateengagement with corrugations of the corrugated conduit sections 10 asshown in FIG. 14 and hereinafter described.

The semicylindrical inner wall 182 of the body portion 164 terminates atits opposite longitudinal edges at a pair of coplanar surfaces 196 and198. The plane in which the surfaces 196 and 198 lie extends through thecenter of the cylinder upon which the semicylindrical inner wall 182 isformed. It should be pointed out that the synthetic resin used forinterconnecting the body portions 162 and 164 forms a hinge 200 aboutwhich these body portions may be folded to open and close the connectorclamp as hereinafter described.

Connected to the external side of the body portion 164 which isconnected to the hinge portion 200 is a locking band, designatedgenerally by reference numeral 202. The locking band 202 is generallyL-shaped in configuration, and includes a first leg 204 secured by athin hinge portion 206 to the body portion 164, and a second leg 208which is secured at substantially a right angle to the leg 204. The legs204 and 208 are joined through a radiused corner 210 which conforms inits radius of curvature to a radiused corner 212 formed along alongitudinal edge at the outer side of the body portion 164. At the freeend of the leg 208 (that is, the end opposite its side connected to theleg 204), the leg 208 carries a latching rib 210 which is configured tosnap into, and register with, the groove 178 in the manner illustratedin FIG. 13.

In the use of the connector clamp 160, as shown in FIG. 14, the endportions of a pair of corrugated conduits 10 are placed in end-to-endrelation, with one side of the conduits in contact with thesemicylindrical inner wall 182 of the body portion 164, and the endfaces of the two conduit sections abutting the stop rib 184. The bodyportion 162 is then folded about the upper side of the two conduitsections 10 until the surface 180b is adjacent and faces the surface198, and the surfaces 186 and 196 are in abutting contact, and extendsubstantially parallel to each other. The locking band 202 is thenfolded about the hinge portion 206 to cause the locking band to bewrapped about the body portion 164, and the latching rib 210 to bebrought into a position of snap engagement with the recess 178. Whensuch snap engagement is effected, the conduit sections 10 are located inend-to-end relation, and are retained firmly in this position by theconnector clamp.

It will be noted in referring to FIG. 14 that as the locking band 202 isfolded about the body portion 164 and positioned to facilitate the snapengagement of the latching rib 210 with the recess 178, the leg 204comes in contact with the locking plates 192, and causes these to bemoved radially inwardly through the slots 188 and 190 until the inneredges of the locking plates, which are arcuate in configuration, seat inand interlock with a pair of adjacent corrugations in the opposedconduit sections 10. Axial sliding movement of the conduit sections 10is thus prevented by this latching engagement of the locking plates 192.

Another embodiment of inlet fitting, also referred to as a male terminaladapter, is illustrated in FIGS. 15 and 16. The inlet fitting 208, ashere illustrated, includes a medial cylindrical body portion 210 whichis characterized in having a smooth outer peripheral wall and a smoothinternal peripheral wall. The medial cylindrical body portion 210 isformed integrally, at one of its sides, with a pair of arcuatelycross-sectioned clamping portions designated generally by referencenumerals 214 and 216. The clamping portions 214 and 216 extend in anaxial direction from the cylindrical body portion 10 and are identicalin configuration to each other. Each of the clamping portions 214 and216 thus includes a hinge portion 218 by which it is hingedly connectedto the body portion 210. The hinge portion is exteriorly defined by aradially inwardly projecting groove 220 formed transversely across theclamping portion to reduce the thickness of the synthetic resin materialat this location and permit flexing of the clamping portion and pivotingmovement inwardly and outwardly with respect to the axis of the inletfitting.

A ramp or beveled or inclined surface 222 extends radially outwardlyfrom each clamping portion from a point adjacent the groove 220 to apoint adjacent a rectangularly cross-sectioned recess or relief 224. Atthe intersection of the ramp 222 and the recess 224, a shoulder 226 isformed. On the radially inner side of each of the clamping portions, aplurality of radially inwardly projecting, axially spaced teeth 228 areformed. It will be noted that the longest of these teeth which projectsthe greatest radial distance into the interior of the inlet fitting islocated adjacent the axial end of the respective clamping portion whichis spaced most distally from the cylindrical body portion 210, and thatthe length of the teeth then diminishes in an axial direction toward thebody portion so that that tooth located nearest the shoulder 226 is theshortest of the teeth and projects the shortest radial distance into thefitting.

Slidably mounted around the body portion 210 for sliding movement fromthat location into a position within the recess 224 (as illustrated inFIGS. 15 and 16) is an annular locking collar 230. The locking collar230 includes a rib 232 which is positioned medially on the radiallyinner side of the locking collar, and is located between two bevels orinclined surfaces provided on the radially inner side of the lockingcollar. This construction permits the locking collar 230 to easily slideupwardly over the ramp 222 from the medial cylindrical body portion 210and into the recess 224.

It will be noted in referring to FIGS. 15 and 16 that the clampingportions 214 and 216 are each disposed on opposite sides of the inletfitting 208 illustrated in these figures so as to be spaced from eachother by 180° around the inlet fitting, and that the two clampingportions are separated from each other by a pair of semi-cylindricalside portions 236 and 238. The semi-cylindrical side portions 236 and238 are formed on segments of circles (in cross-section), and thusdefine with the clamping portions 214 and 216, a hollow cylindrical bodywhich is adapted to receive an end of one of the corrugated conduitsections 10 hereinbefore described.

On the opposite side of the cylindrical body portion 210 from the sideto which the side portions 236 and 238 and clamping portions 214 and 216are attached is a necked down portion of the fitting 208 which defines aradially inwardly extending, annular shoulder 240. The shoulder 240 isjoined at its inner side to an axially projecting, externally threadednipple 242. The outside diameter of the external threads 244 formed onthe nipple 242 is such that the nipple may be passed through the opening246 formed in one of the side walls 248 of an electrical box. Theradially inwardly extending shoulder 240 forms a stop or abutmentpreventing the remaining portion of the inlet fitting 208 from passingthrough the opening 246.

When the inlet fitting 208 is mounted within the opening 246 in the sidewall of an electrical box, the externally threaded nipple 242 is passedthrough the opening 246 until the shoulder 240 abuts the O-ring 250. Atthis time, a threaded locking bushing 252, shown in dashed lines in FIG.16, is threaded on the nipple 242 to firmly lock the inlet fittingwithin the opening 246 of the box 248.

With the inlet fitting 208 locked in position in the opening 246 in thebox 248 by means of the bushing 252, the clamping portions 214 and 216are permitted to flare out to a location which is divergent with respectto the axis of the inlet fitting. At this time, the locking band 230 hasbeen slid along the fitting to a position where it surrounds the medialcylindrical body portion 210. The end portion of a corrugated conduitsection 10 is then inserted into the open end of the fitting between theside portions 236 and 238. The lengths of the teeth 228 formed on theinternal surface of each of the clamping portions 214 and 216 andprojecting radially inwardly therefrom are dimensioned so that at thistime the teeth closest to the pivotal axis of each of the clampingportions, though positioned closest to the axis of the inlet fitting,are shortest in length and thus do not interfere with the insertion ofthe end portion of the corrugated section 10 into the opened fitting.

After the conduit section has been firmly seated, in most instancesagainst the radially inwardly extending shoulder 240, the locking collaror band 230 is slid axially along the inlet fitting 208 until it ridesup over the ramps 222 on the outer surface of each of the clampingportions 214 and 216 and thus biases these clamping portions inwardlyabout the hinge portion 218 of each. Finally, the locking collar or band230 is slipped into the recesses 224 so as to lock the clamping portions214 and 216 firmly in position where they are in alignment and completea cylindrical figure with the side portions 236 and 238. At this time,the teeth 228 firmly engage the corrugations in the corrugated conduitsection 10 which has been inserted in the fitting to lock it in positionand prevent it from being released from the fitting.

Although certain preferred embodiments of the invention have been hereindescribed in order to illustrate the principles of the invention, itwill be understood that various changes and innovations can be made inthe illustrated and described structure without departure from the basicprinciples of the invention. For example, in using the several systemfittings herein described, it may, in some installations andapplications, be desirable to use solvent bonding to join sections ofconduit to each other in end-to-end relation, or to join the end portionof one or more conduit sections to or through a particular fitting. Thistechnique is generally well understood in the art, and where it might beused in the system of the invention, does not, per se, constitute anovel aspect thereof. Changes and innovations which continue to relyupon and include one or more of the novel features of the system of theinvention are thus contemplated, and such modified systems are thereforedeemed to be circumscribed by the spirit and scope of the inventionexcept as the same is necessarily limited by the appended claims orreasonable equivalents thereof.

What is claimed is:
 1. An inlet fitting for engaging a corrugated tubingsection to an electrical box having an opening in a side wall thereofcomprising:a generally cylindrical body severed along parallel, axiallyextending lines to define a pair of opposed clamping portions of arcuatecross-sectional configuration pivotable radially outwardly relative tothe axis of the cylindrical body, said cylindrical body furtherincluding a medial cylindrical body portion having one side connected toone of the ends of each of said clamping portions, and having anopposite side, each of said clamping portions including:a plurality ofaxially spaced, radially inwardly extending teeth projecting toward theaxis of the cylindrical body from the radially inner side of therespective clamping portion; a hinge section of radially reducedthickness adjacent said medial cylindrical body portion and connectingsaid one end of the respective clamping portion to said cylindrical bodyportion to hingedly interconnect the respective clamping portion to themedial cylindrical body portion for radial pivotation of the respectiveclamping portion about said hinge section of radially reduced thickness;a free end opposite said one end of the respective clamping portion; aninclined surface sloping radially outwardly from a relatively thinradial section to a relatively thick radial section in an axialdirection from a location adjacent said hinge section toward the freeend of the respective clamping portion, said inclined surfaceterminating in a first radially extending shoulder spaced axially fromthe free end of the respective clamping portion and spaced axially fromsaid teeth toward said hinge section; and a radially outwardlyprojecting end portion of the respective clamping portion adjacent thefree end thereof spaced from said shoulder and defining with saidshoulder a locking collar-receiving recess extending transversely acrossthe clamping portion, said recess having a bottom which is in coplanaralignment with the external surface of said generally cylindrical body;a cylindrical nipple of smaller diameter than said cylindrical body; asecond radially extending shoulder extending between, andinterconnecting, one end of said nipple with a side of said cylindricalbody opposite the side thereof connected to said clamping portions; andan annular locking collar having a greater internal diameter than theouter diameter of said cylindrical body mounted on, and surrounding,said cylindrical body, and axially slidable on said cylindrical body toa position around said clamping portions in which said locking collar isretained in said recesses to retain said clamping portions in aconduit-engaging position extending parallel to the axis of thecylindrical body, said annular locking collar including a radially innersurface adapted to cooperate with said inclined surface to allow saidlocking collar to be slid over said inclined surface as said lockingcollar is moved axially from a location adjacent said second radiallyextending shoulder, across said inclined surface, into the recesses ofsaid clamping portions.
 2. An inlet fitting as defined in claim 1wherein said nipple is externally threaded and wherein said inletfitting further includes a locking bushing threadedly engaged with saidnipple.